I’ve probably purchased 300 books in the last year for research purposes, not to mention all the fiction my wife gets (and so do I, if it costs $3 or less). For the newer ones , buying them as eBooks is generally an option. But the state of software, DRM, and copy protection for Kindle books is a mess. Kindle’s software (like iBooks) is deliberately crippled – no copying into another document, no printing, and especially no way to copy diagrams. I’m running Kindle’s software on my Mac and on an iPad, rather than using a Kindle tablet, but that barely helps.